Crystals of alumina sulfate can be obtained by treating minerals containing alumina with sulfuric acid, extracting aluminum salts from the minerals-and crystallizing aluminum sulfate from the extracted solution. Crystalline sulfate can also be obtained together with iron sulfate from waste sulfuric acid or the like which contains considerable amount of iron and aluminum. However, aluminum sulfate crystals cannot be separated easily from crystals of the other metals in these processes.
Herefore, technically pure aluminum sulfate crystals have been generally obtained by crystallizing the impure aluminum salts from previously purified aluminum sulfate solutions. However, these purification procedures have been troublesome and it has been difficult to obtain pure aluminum sulfate crystals inexpensively by such prior art methods. A need, therefore, continues to exist for a simple, low-cost method of obtaining pure, crystalline aluminum sulfate.